Alternating current motor and controller



Aug. 26, 1941. c. STONEHILL 2,253,951

ALTERNATING CURRENT MOTOR AND CONTROLLER Filed Aug. 23, 1959 INDUCTION-H'OTO R MAIN WINDING In ventor:

Cyrus Stonehil y)? 6? His A torney.

- motor and a transformer-type controller.

Patented Aug. 26, 1941 ALTERNATING CURRENT MOTOR AND CONTROLLER CyrusStonehill, Fort Wayne, 1:16., assignor to General Electric Comp New Yorkany,- a corporation of Application August 23, 1939, Serial No. 291,529

a Claims.

My invention relates to alternating-current motors and controllers andconcerns particularly single'phase induction motor systems.

It is an object of my invention to provide an improved, simplifiedcontroller and connection for self-starting variable speed single-pha-sealternatingwurrent motors in which there will be no necessity for shortcircuiting turns, or any likelihood thereof, and in which there is noneed for pigtail connections or power-wasting carbon brushes. Other andfurther objects and advantages will become apparent as the descriptionproceeds.

In carrying out my invention in its preferred form I utilize acondenser-type of induction The motor has a main or running winding andan auxiliary or condenser winding displaced in space phase from therunning winding. The controller is provided with separate oppositelywound windlugs and a slider for making adjustable connections betweenadjacent points on the two transformer windings to control the motorspeed. The motor windings are interposed. in connections between theends of the transformer windings.

The invention will be understood more readily from the followingdetailed description when considered in connection with the accompanyingdrawing and those features of the invention which are believed to benovel and patentable will be pointed out in the claims appended hereto.The single figure of the drawing is an electrical circuit diagramrepresenting an embodiment of my invention.

The conventional type of single-phase induction motor may be employedhaving a main or running winding ll, an auxiliary or condenser winding12 and a phase splitting or modifying device such as a reactance in theform 01' a condenser lt in series with the auxiliary winding l2, all ofwhich parts are shown within the dotted rectangle M. For the purpose ofproviding a starting connection and for varying the speed of the motor Iprovide a controller ldhaving a pair of windings l8 and II,respectively. The controller or transformer I! may include also suitablewindings for adapting a motor wound for a given voltage to a differentsupply voltage. For example, the winding l8 may be connected in serieswith another winding It or may form a section of a transformer coil withan intermediate tap such that the windings l6 and II tostep-down autotransformer, and the winding 1% alone forms the 110 volt winding of sucha transformer, assuming the controller to be used for an induction motorhaving a normal rating of 110 volts. The winding i6 is thus conductivelyconnected to the 229 volt supply circuit so as to be conductivelyenergized thereby; whereas the winding H is inductively coupled. Formaximum simplicity of construction and ease of operation the windings l6and H are preferably oppositely wound and arranged one alongthe other, I

for example, on the same core, and for varying the connections a slideri8 is provided carrying sliding contacts 20 and 2! cooperating withstationary contacts or scraped turns ofthe transformer windings l6 andII, respectively. The terminals at the ends of each of the windings l8and i1 have one of the motor windings connected across them. Forexample, the motor winding ll may be connected between the right handends of the windings I6 and I1, and the motor winding I2 with thecondenser l3 in series, may be connected across the left hand ends ofthe transformer windings l6 and H. The arrangement is such that as theslider I9 is moved in one direction or the other more of the windings l5and II is out into one of the motor-winding circuits, and less is cutinto the other of the motor-winding circuits, each motor-winding circuithaving portions of each of the controller windings i6 and H connected inseries with it.

With the slider l9 shown approximately in the central position R. andwith the assumed voltages it will be seen that approximately 110 voltsis applied in each of the motor winding circuits. The slider I8 ispreferably in the central position when the motor is started in order tohave approximately full rated voltage applied to the motor. The speedvariation of the motor I4 is obtained by moving the slider IS in onedirection 1 or the other, it being understood that the greater thevoltage applied to the main winding H the greater the speed. The lowerthe desired operating speed the greater the need for quadrature fieldfor adequate torque, and accordingly the greater the voltageautomatically applied to the auxiliary or quadrature winding II. Forexample, to operate the motor at low speed, slider 18 may be moved tothe right to the position marked b in which relatively small numbers ofturns of the windings I8 and II will be connected in series with themain winding II and a relatively large number of turns will be connectedin series with gether form the primary 220-volt winding 01' a theauxiliary winding II. -For instance, at the connections between themotor windings and the controller or transformer windings are made ineither the motor or the transformer, each of the transformer windings i6and is wholly independent of the other, except for the inductive rela-'tion. Consequently, there are no short circuitecl turns for any positionof the controller. Fur thermore, there is no need for the slidingcontactors 20 and 2| to bridge contacts in going from one position tothe next, and consequently there is no need for short circuiting ofturns in going from one speed setting to the other or for using carbonbrushes to minimize short circuit currents. Since the variableconnections from one transformer to the other are made directly by theslider I9 there is no need for pigtail or other power wasting devices,and the construction, therefore, provides the utmost in simplicity anddurability.

In accordance with the provisions of the patent statutes, I havedescribed the principle of operation of my invention together with theapparatus which I now consider to represent the best embodiment thereofbut I desire to have it understood that the apparatus shown is onlyillustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An induction motor having a main winding and an auxiliary windingdisplaced in space phase, a phase modifying device connected in serieswith the auxiliary winding, a transformer having a winding adapted to beconductively connected to a supply circuit and an oppositely woundsecond winding in inductive relation to the first, lying along the saidfirst winding so that successive points on the second winding lie alongsuccessive points on, the first, and a slider for electricallyconnecting points of the second transformer winding to adjacent pointsof the first transformer winding, said main motor wind ing beingconnected between one end of the first of said transformer windings andthe corresponding end of the second of said transformer windings andsaid auxiliary motor winding and phase modifying device being connectedbetween the remaining ends of said transformer windings.

2. An altemating-current motor having a main stator winding and anauxiliary stator winding displaced in space phase, a condenser connectedin series with the auxiliary winding, a transformer having a windingadapted to be conductively connected to a supply circuit and a secondwinding in inductive relation to the first, adjustable connections tointermediate portions of said transformer windings, and a conductorjoining said adjustable connections, conductors connecting the mainmotor winding in series with a portion of the first of said transformerwindings between the end and intermediate ad- ,iustable connection and aportion of the second transformer winding between the adjustableconnection and the end of the winding such as to apply series voltagesaiding each other in the main motor winding circuit, conductorsconnecting the auxiliary motor winding and the condenser in series withthe portions of said transformer windings between the adjustableconnections and the remaining ends of said windings, whereby seriesvoltages aiding each other are applied also in the auxiliary motorwinding circuit, and means for simultaneously moving said adjustableconnections in such a direction as to increase the series voltagesapplied to one of said motor windings and to decrease the seriesvoltages applied to the other of said motor windings.

3. An alternating-current motor having a main stator winding and anauxiliary stator winding displaced in space phase, a condenser connectedin series with the auxiliary winding, transformer having a windingadapted to h iltOIldllC- tively connected to a supply circuit and secondwinding in inductive relation to the first, adjustable connections tointermediate portions of said transformer windings, a conductor joiningsaid adjustable connections, conductors connecting the main motorwinding in series with a por tion of the first of said transformerwindings between the end and intermediate connection and a portion ofthe second transformer winding between the adjustable connection and theend of the winding such as to apply series voltages aiding each other inthe motor winding circuit, conductors connecting the auxiliary motorwinding and the condenser in series with the portions of saidtransformer windings between the adjustable connections and theremaining ends of said windings, whereby series voltages aiding eachother are applied also in the auxiliary motor winding circuit, and meansfor moving said connections along said transformer windings.

4. An alternating-current supply circuit having a given voltage, analternating-current motor wound for a given voltage, a controller havingan auto-transformer winding including a group of turns forming a firstcontroller winding wound for said supply circuit voltage and including agroup of turns forming a second controller winding wound for the voltageof said motor, and a third controller winding independent of the saidtwo groups of'turns wound for the voltage of said motor, an adjustableconnection between intermediate points on the last two mentionedwindings, said first controller winding being connected across saidsupply circuit, said motor hav-- ing a main winding connected betweenone end of said second controller winding and the end of the thirdcontroller winding giving a voltage which will act to aid the voltage ofthe second controller winding in series therewith in the motor circuit,said third controller winding being so wound with respect to the secondthat the said series voltages increase or decrease as the adiustableconnection is moved in one direction or the other, the motor having alsoan auxiliary winding and a condenser connected in series between theremaining ends of the second and third controller windings, wherebyvariation of the adjustable connection between the controller windingsproduces variations in the starting torque and speed of the motor.

CYRUS STONEIIHJLI.

